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Patented July 29, 1952 a,fi-DICHLOROETHYLSILANES Leo H. Sommer, StateCollege, Pa., assignor to Dow Corning Corporation, Midland, Mich., a

corporation of Michigan No Drawing. Application June 3, 1949, Serial No.97,085

4 Claims.

The present invention relates to chlororganic derivatives of silicon.

The chlorination of organic derivatives of silicon has been referred toin the literature. When a methylchlorosilane is chlorinated, thechlorine selectively chlorinates any methyl radical which is alreadychlorinated. The polychlorinated radical so obtained is unstable. I havefound that in the chlorination of ethylchlorosilanes the chlorine alsochlorinates previously chlorinated radicals with the principal productbeing the [Ledichloroethylchlorosilane. This material is relativelyunstable and is not a satisfactory intermediate for many uses.

Compounds in accordance herewith correspond to the general formulaC1CH2CHC1slR3nCin in which n has an average value of from to 3 inclusiveand in which R represents alkyl.

Compounds of this type as is to be seen from the above formula containthe monovalent 11,18- dichloroethyl radical. This radical, it has nowbeen found, is relatively stable. Such compounds containing this radicalare of substantial use as intermediates in the preparation of siloxanepolymers and copolymers and in the production of compounds such asa-ChlOlOViIlYlSlliCOIl compounds.

While the fl,5-dichloroethyl silanes are the product of chlorinatingethyl silanes, it has been found that the a,,6-dichloroethy1 compoundsmay be prepared in excellent yield by the chlorination of vinyl silanes.The vinyl derivatives of silicon and their preparation are known. Thus,Ushakov, in the Journal of General Chemistry (USSR) at volume 7, pages24922l98, shows the chlorination to produce an a-chloroethylsilane andthe dehydrohalogenation thereof to produce vinyl silane.

The chlorination of the vinyl silicon compounds may be conducted by thedirect chlorination thereof with chlorine gas. The rate of the reactionmay be increased by customary means as by radiation with ultravioletlight or by the use of a catalyst.

As indicated by the general formula above stated, the compounds hereofare those which contain one e-dichloroethyl radical and a total of threealkyl and chloro radicals or atoms linked to the silicon. The alkylradicals so linked to the silicon may be of any desired length as forexample from methyl to octadecyl. When the silane contains three alkylradicals, the compound is substantially non-functional except for thechlorines of the dichloroethyl radical. Those silanes which containchlorine linked directly to the silicon are functional both with respectto the chlorines of the dichloroethyl radical and with respect to thechlorines linked to the silicon. These latter silanes are of utility inthe production of siloxane polymers and copolymers.

Exmaple 1 Chlorine was passed through 26 g. of vinyl trichlorosilane ina reaction vessel equipped with a reflux condenser. As the concentrationof chlorine increased, the rate of chlorination increased with theliberation of heat. The reaction mixture was cooled to preventoverheating. The chlorinated product was fractionated with the followingfractions being obtained.

TC. Gr. Pressure Cuts 2 and 3 were found to bes-dichloroethyltrichlorosilane.

Example 2 Vinyltrimethylsilane was prepared by reaction of a methylGrignard reagent and vinyltrichlorosilane. grams of thevinyltrimethylsilane so obtained were chlorinated by passing chlorinegas thereinto. The temperature was maintained below room temperatureduring the reaction. The chlorinated product was fractionated. Thedesired c, 3-dichloroethyltrimethylsilane was obtained and was found tohave a boiling point of 61 C. at 13 mm. pressure, a. density of 1.0570,an index of refraction at 20 C. of 1.4617 and a melting point of l5 C.

When the vinyltrichlorosilane is partially methylated the compoundsmethylvinyldichlorsilane and dimethylvinylchlorsilane are obtained.These may be chlorinated whereby to obtain 11,18-dichlorethylmethyldichlorsilane and a,;3-dlclll0lethyldimethylchlorsilane.

3 4 That which is claimed is: the silane in liquid phase, whereby toproduce the 1. Compounds of the general formula correspondinga,pdichlorethy1silane.

clcmcnclsmmcln LEO SOMMER- where n has an average value of from 0 to 3in- 5 REFERENCES CITED elusive and R, is an alkyl radical.

. The followmg references are of record in the 3. cicmcnclsucnm. e Pa en4. The method which comprises reacting free Sommer et 2.1., C m- 6-. VOL

chlorine with a vinyl silane of the general formula 10 (1948) pages2872-2874.

CH2 CHSiR3nC1n where n has an average value Agre, Jour. Am. Chem. Soc.,vol. 71, (1949) of from 0 to 3 inclusive and R is an alkyl radical,pages 300-304.

by contacting the chlorine and the silane, with

1. COMPOUNDS OF THE GENERAL FORMULA